The problem of refocusing or focus manipulation after shooting an image is addressed. There are several scenarios where the need for refocusing is essential. The main scenario occurs when, during the shoot, the camera is focused on an object different than the one that the photographer had in mind. Moreover, even if the correct object was in focus, the photographer may want to change the focus position after the fact. Therefore, the existence of such an option provides the photographer with the freedom to choose the subject in focus after the shoot, even if the camera was focused on the intended subject.
Furthermore, focus manipulation may involve much more than just refocusing. Focus manipulation provides the ability to create images that a real camera cannot shoot. For example, it may be possible to allow focusing on some subjects and not focusing on others, even if the non-focused subjects are between the focused subjects.
Another option that focus manipulation may provide is the ability to create an all focus image, i.e., an image where all the objects are in focus.
One possible solution to focus manipulation issues is the so-called plenoptic camera which catches the entire light field of the scene and may be focused at any point after shooting the image. Plenoptic cameras however use non-standard camera optics and need sensors with a very large number of pixels.
Thus, a focus manipulation methodology using standard sensors and conventional camera optics is needed.